Express-session not persistant - node.js

Question

In my App.js, I have set the session for user authentication, and in my user.js, I add the username to my session. However, when I print out my req.session, it does have a req.session.username in it, but in my two app.use() that prints out the session, there is no req.session.username. Is there something wrong with how my sessionOptions are set up? Or is there some other problem?
import express from 'express';
import bodyParser from 'body-parser';
import mongoose from 'mongoose';
import cors from 'cors';
import diaryRoutes from './routes/diarys.js';
import userRoutes from './controllers/user.js'
const app = express();
app.use(express.json());
// app.use(express.urlencoded({ extended: false }));
// app.use(bodyParser.json({ limit: '30mb', extended: true }))
// app.use(bodyParser.urlencoded({ limit: '30mb', extended: true }))
app.use(cors());
import session from 'express-session';
// after login, don't have to enter username and pw again
// ...so sessions
const sessionOptions = {
secret: 'secret for signing session id',
saveUninitialized: true,
resave: false,
cookie: { secure: false }
};
app.use(session(sessionOptions));
app.use((req, res, next) => {
console.log('session contains', req.session);
next();
});
// have middleware that deserializes the logged in user
// if req.session.user exists, then create property req.user that contains the user obj
app.use(async (req, res, next) => {
console.log(req.session, ' is middleware req.session');
if(req.session.username) {
req.user = await User.findOne({username: req.session.username}).exec();
}
next();
});
app.use('/diarys', diaryRoutes);
app.use('/users', userRoutes);
const CONNECTION_URL = 'some url';
const PORT = process.env.PORT || 5000;
mongoose.connect(CONNECTION_URL, { useNewUrlParser: true, useUnifiedTopology: true })
.then(() => app.listen(PORT, () => console.log(`Server Running on Port ${PORT}`)))
.catch((error) => console.log(`Error message(can't connect): ${error}`));
import express from "express";
const router = express.Router();
import argon2 from "argon2"
import mongoose from 'mongoose';
const User = mongoose.model('User');
router.post('/Login', async (req, res) => {
const {username, password} = req.body;
const user = await User.findOne({username: username}).exec();
console.log('LOGIN: existingUser', user);
if(user) {
// user.passwordr is from db, password is incoming pw
if(await argon2.verify(user.password, password)) {
// this creates our "authenticated" session
// "serializing" the user
req.session.username = user.username;
console.log(req.session,' is req.session');
res.json(user);
} else {
res.status(400).json({error: 'login failed'});
}
} else {
res.status(400).json({error: 'login failed'});
}
});
// promise --> async task
// promise is resolved w/ some value
// async --> function is async
// await ... wait for a promise to be resolved... when it does resolve evaluate to the
// the resolved value
router.post('/Register', async (req, res) => {
console.log(req.user, ' req.user');
const {username, password} = req.body;
console.log(username, password);
// console.log(username, password, 'is username password for register')
const existingUser = await User.findOne({username: username}).exec();
if(!existingUser) {
const hash = await argon2.hash(password);
const savedUser = await (new User({username, password: hash})).save();
res.json(savedUser);
} else {
res.status(400).json({error:'could not register'});
}
});
export default router;